Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

008
FXUS63 KLOT 142320
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
620 PM CDT Tue Jul 14 2026

.KEY MESSAGES...

- Hot conditions are expected for much of the week; though
  somewhat cooler near Lake Michigan.

&&

.DISCUSSION...
Issued at 223 PM CDT Tue Jul 14 2026

An expansive area of high pressure continues to reside over the
Midwest and Great Lakes regions which will continue to promote
warm and humid conditions. Temperatures will continue to warm
into the mid to upper 90s this afternoon with heat indices
peaking around the 100 degree mark. While there is a lake breeze
oozing inland northeast IL and northwest IN, the inland extent
of the lake breeze should be limited given the weaker flow
behind it and thus limit lake cooling effects to the immediate
shoreline.

Similar conditions are expected for Wednesday with highs once
again back into the mid-90s inland with slightly cooler readings
(highs in the upper 80s) near the immediate lake shore due to a
lake breeze. However, forecast soundings do show slightly
better mid-level moisture in place which may lead to the
development of some diurnal cumulus clouds. Additionally, some
of the wild fire smoke from Canada is progged to round the high
pressure and ooze into the area from the east which may further
aid to add some haze to the sky and limit some of the incoming
solar radiation. While the clouds likely won`t have much effect
on temperatures on a widespread basis, they may be able to keep
temperatures a degree or two cooler in spots that see more
clouds and thus result in slight lower heat indices there too.
Speaking of heat indices, dew points on Wednesday will once
again start off in the lower 70s but should mix down into the
upper 60s through the afternoon which will keep peak heat
indices around the 100 degree mark once again. Given that our
local Heat Advisory criteria is 105 degrees and above, we will
be holding off on issuing any heat headlines for tomorrow but
will continue to message the heat and encourage everyone to stay
hydrated and avoid outdoor activities during the hottest parts
of the day.

Heading into Thursday, the high will begin to move east as
deeper troughing builds over Ontario and Quebec. At the same
time, moisture will be trying to return northward out of the
southern CONUS and Gulf. Given that forecast soundings continue
to show the deeper moisture still being somewhat limited and the
idea that the high should still have majority control, suspect
that any showers and storms that try to develop will be very
isolated and mainly confined to our far southern and western CWA
closer to the northwestward propagating shortwave. With the
expectation for more cloud cover on Thursday temperatures will
still be warm but a few degrees cooler than Wednesday with highs
in the lower 90s. As a result heat indices will also be a bit
lower (peaking in the 95-100 degree range) as dew points should
once again mix down into the upper 60s to lower 70s which will
once again keep us below heat headline criteria. Furthermore,
with a signal for a more enhanced lake breeze on Thursday highs
near the lake should be more into the mid to upper 80s which
will further cap heat indices here into the lower to mid- 90s.
This expectation will keep Chicago and Cook County below their
three day Extreme Heat Warning Criteria so will forego any such
issuance on this shift, but continue to message the heat and
need for folks to stay hydrated.

By Friday the high will be far enough east to allow the
northwest flow aloft to take control and pivot another shortwave
trough through the area. This wave in combination with better
moisture and instability should result in a broader coverage of
showers and thunderstorms Friday afternoon and evening. Though,
with the weaker wind shear the threat for severe weather
continues to look low. Additional periods of showers and
thunderstorms are expected through the weekend and into the
early part of next week as shortwaves continue to traverse the
pattern and dive through the region. Temperatures through the
end of the week are expected to remain near to above average
with daily highs in the upper 80s and 90s.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 620 PM CDT Tue Jul 14 2026

Key messages for the 00Z TAF period:

* A lake breeze is expected to pass over the Chicago terminals
  and GYY on Wednesday

Light winds will favor a W direction through the night but may
go variable at times. Winds will start out W on Wednesday before
going E behind a lake breeze, less than 10 kt all the while.
Wind shift is slated for early afternoon at GYY and mid-
afternoon at the Chicago sites. Expect VFR throughout the
period.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Air Quality Alert until midnight CDT Wednesday night for
     ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ021-ILZ103-ILZ104-
     ILZ105-ILZ106-ILZ107-ILZ108.

IN...Air Quality Alert until midnight CDT Wednesday night for
     INZ001-INZ002-INZ010-INZ011.

     Air Quality Alert from midnight tonight to 1 AM EDT Thursday
     for INZ019.

LM...None.

&&

$$

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